Conventional speaker systems are often formed, for instance, from a material such as wood particle board. It is characteristically the case that the cabinet is box-like in appearance, covered with a suitable wood or plastic veneer, and has an opening in the front thereof leading into what constitutes a sound chamber, the opening usually being covered by a grill cloth, a polyurethane foam pad, or some other equally effective and aesthetically pleasing material or device. Moreover, conventional speaker systems usually include one or more drivers mounted within the sound chamber in confronting relation to the opening in the cabinet.
While the evolution of speaker systems has been significant, it has remained difficult to match a driver and a cabinet in a highly predictable fashion. It is true, of course, that theoretical formulas have been developed for this purpose utilizing the measurements of a given driver, the volume of the cabinet, the cabinet tuning, the bass cutoff, the system efficiency, etc., and the basic theoretical formulas have been further refined and expanded by the use of computer techniques. Despite this knowledge, the state of the art has not advanced significantly in recent years due to a particularly vexing problem.
Specifically, speaker cabinets oftentimes resonate in conventional speaker systems. This has proven to be true, not only with particle board cabinets, but also with cabinets made from other conventional materials for speakers such as solid wood, plastic and the like, with the result that conventional speaker systems characteristically have higher distortion and lower efficiency than would ideally be the case. In order to overcome the resonance problem, attempts have been made to utilize sound absorbing or damping materials with cabinets.
Among the numerous attempts to alleviate the problems associated with resonating cabinets by means of the use of sound absorbing or damping materials are those disclosed in U.S. Pat. Nos. 4,213,515; 4,167,985; 3,430,728; 3,326,321; and 2,903,084.
Unfortunately, the numerous attempts to overcome the problem of resonating cabinets in speaker systems have been less than completely satisfactory for a common reason. They have all failed to recognize that, while the sound absorbing or damping materials may serve to absorb sound waves that might otherwise cause vibrations or resonance in the cabinet, this material has usually been less than totally effective in preventing resonance of the cabinet constructed, for instance, of wood particle board which has a tendency to resonate at relatively low frequency, and the sound absorbing or damping material also absorbs a portion of the sound wave energy intended to be emitted from the speaker system for the listening pleasure of those utilizing the system, rather than resisting the potential resonance inducing characteristics of the sound waves. Stated simply, it has not previously been recognized that the most advantageous way of dealing with the problem of resonating cabinets in speaker systems is to utilize a reinforcing liner to resist resonance by providing a rigid, well-braced box.
Accordingly, it is an object of the present invention to provide a speaker cabinet comprising a cabinet with a resonance resistant liner.
Another object of the present invention is the provision of a speaker cabinet of the type described wherein the resonance resistant liner is adapted to reinforce the cabinet to substantially preclude resonance.
A further object of the present invention is the provision of a speaker cabinet of the type described wherein the resonance resistant liner does not absorb sound wave energy in order to substantially preclude resonance.
Still another object of the present invention is the provision of a speaker cabinet of the type described wherein the sound chamber within the cabinet is substantially lined with a cement-like mixture.
These and other objects, features and advantages of the present invention will become apparent from the following description when considered in connection with the accompanying drawings.